Voltage referenced electrical conductors or transmission lines must be uniform, properly terminated and isolated from each other to avoid electromagnetic interference between adjacent circuits. Such interference can result in undesirable electrical and electromagnetic distortions and slower response times. This not only reduces the efficiency of the circuit, it may result in the transmission of erroneous data signals. This is especially important in state-of-the-art microminiaturization in that as the size of circuits is substantially reduced and as the output requirements of high speed circuits are increased, the problems associated with electromagnetic interference are magnified.
Various attempts have been made in the prior art to interconnect circuits and isolate the conductors or transmission lines thereof. For example, U.S. Pat. No. 3,351,816 to Sear et al discloses a circuit board-type construction with electrically isolated coaxial conductors which are shorted together. Specifically, the patent discloses a rigid multi-board structure having defined mating channels which receive the dielectric material and the circuit pattern and permit the conductors to be shielded from one another. Griff U.S. Pat. No. 3,837,074 discloses the electrical isolation of conductive members utilizing a sheet of flowable dielectric material formed from a mixed thermoset/thermoplastic resin. When cured it forms a dielectric exhibiting elastomeric properties. The elastomeric dielectric is then used to fill a dielectric trough and surrounds a conductor disposed therein to electrically isolate the conductor. Older et al. U.S. Pat. No. 3,922,479. discloses a coaxial circuit construction wherein the conductor is surrounded by several layers of insulating polymers which are surrounded by several layers of metal. These references, however, fail to disclose the isolation of conductors or transmission lines by shielding them with conductive reference layers isolated by a dielectric layer, and a method of making them.
In accordance with the foregoing, it is an object of the present invention to provide a miniature electric assembly for isolating transmission lines and a method for producing such an assembly.
It is another object of the present invention to provide a miniature electric assembly and method of making it that utilizes a pair of isolating conductive reference layers that are separated by a dielectric layer.
It is a still further object of the present invention to provide an electric assembly and method of making it that utilizes a pair of conductive reference layers that are separated by a dielectric layer and where a conductor is encased and supported along its length by a pedestal dielectric base.